In a typical fossil fuel utility plant, fossil fuel is burned using combustion air, and cooling water, to provide electric power, and, as byproducts, process heat and `dirty` stack gas which typically includes CO.sub.2, SO.sub.2, NO.sub.X, H.sub.2 O, N.sub.2 and O.sub.2. Many electric power generating plants are equipped to clean stack gases, and to recover at least some of the process heat. Where the market for electric power which could be served from the plant varies, e.g. by time of day or seasonally, it has become typical to design and operate the plant to produce some fraction below 1.0, of the marketable power which is neither as small as the minimum load that the system depending on the plant ever experiences, nor as much large as the maximum load experienced, or, with projected growth, could be expected to be experienced in that system.
For dealing with the variable load which is above or below that fraction, different electric power providers employ different strategies. One is to operate additional electric power generating equipment (e.g. as turbine-powered generators) only during peak load periods. Obviously, that solution requires considerable capital investment in facilities which may remain idle much of the time. Another strategy which is popular, is buying power generated by others, and selling to others excess power. This strategy depends on peak loading being out of phase from one generating plant to another. Yet another strategy is pumped storage or some conceptually similar way of putting aside for use during a time of greater demand, some of the electric power that is generated during a time of lesser demand, and vice versa. In that sense, a fossil fueled electric power generating plant and its distribution system, considered as a whole, can be considered to produce excess off-peak electric power, and to have a capability to consume on-peak electric power.
The present invention is concerned with providing a comprehensive energy system which has one or more fossil fueled electric power generating plants as an integral component. Where, in the text and drawings, a `utility plant` is mentioned, that mention is meant to encompass both a physical reality in which one fossil fueled electric power generating plant is used, and a physical reality in which a plurality of such plants are operated in a coordinated manner.
Hanrahan et al, in U.S. Pat. No. 5,219,671, issued Jun. 15, 1993 have disclosed a steam/bromine/HBr system for hydrogen generation and utility load leveling for a utility plant. A methane-assisted version of such a system is disclosed in the copending U.S. patent application of Hanrahan et al, application Ser. No. 08/835,233, filed Apr. 7, 1997, now U.S. Pat. No. 5,833,834. In both systems, inputs of process heat, water, off-peak power and HBr, are used for providing outputs of H.sub.2, O.sub.2, Br.sub.2 and on-peak electric power. The methane-assisted system has methane as an additional input, and CO.sub.2 as an additional output.
The comprehensive energy system of the present invention is intended to incorporate either such system for hydrogen generation and utility load leveling for a utility plant.
The Parker, U.S. Pat. No. 5,443,804, issued Aug. 22, 1995 discloses a system for recovering CO.sub.2 from a cleaned utility plant stack gas, and providing an output of liquid methanol, which is useful as an automotive internal combustion engine fuel or fuel ingredient (possibly after some modifications if the engine was designed to run on gasoline).
The comprehensive energy system of the present invention is intended to incorporate such a system for recovery of CO.sub.2 and synthesizing methanol.
Lastly, the Mark 13 process, disclosed in a research paper by Van Zelzen et al, and in a 1979 U.K. patent of Van Zelzen et al discloses a system for desulfurizing stack gas and producing hydrogen as an output.
The present invention contemplates operating a Bunsen reactor having some similarities to the Van Zeizen et al system, for cleaning stack gas, converting Br.sub.2 to HBr, and producing H.sub.2 SO.sub.4, and operating such a reactor in conjunction with a utility plant Br.sub.2 -steam-methane unit, and a CO.sub.2 recovery-methanol synthesis unit, for providing a comprehensive energy system.